1. Field of the Invention
The present invention relates to a polarizing member and an optical member, in which sticking can be prevented while an adjacent optical sheet can be prevented from being injured, and which are adapted for formation of a liquid-crystal display device, or the like.
The present application is based on Japanese Patent Application No. Hei. 11-221388, which is incorporated herein by reference.
2. Description of the Related Art
Further reduction in thickness, increase in size and improvement in luminance are required in a liquid-crystal display device. If a side-light type light pipe for forming a back-lighting device is made thin or large-sized for the purpose of reduction of thickness or increase of size, lowering of luminance may be however caused. Therefore, a measure to improve light-utilizing efficiency to thereby improve luminance is taken as the following method. That is, a prism sheet and a reflection type polarizing plate are disposed on a back-lighting device so that outgoing light from the back-lighting device is imported into the reflection type polarizing plate while the optical path of the light is controlled by the prism sheet. The outgoing light is converted into polarized light by the reflection type polarizing plate, so that the polarized light is supplied to an absorption type polarizing plate. In this case, reduction of thickness can be achieved when the reflection type polarizing plate and the absorption type polarizing plate are laminated and integrated with each other to eliminate interposition of space.
However, if the reflection type polarizing plate is disposed on the prism sheet, interference fringes appear or the reflection type polarizing plate and the prism sheet stick to each other to thereby cause a sticking phenomenon. Hence, there is a problem that display quality is lowered. If an anti-glare layer for preventing glaring light is provided on the visual side to prevent sticking, the prism sheet is injured or damaged by the concave-convex structure of the anti-glare layer. Hence, there is a problem that the injury or damage of the prism sheet formed a scattering point, or the like, to disturb the optical function to thereby cause extreme lowering of the display quality.
An object of the present invention is to develop a reflection type polarizing plate which can prevent a prism sheet adjacent to the polarizing plate from causing interference fringes and from being injured, and which can prevent the adjacent prism sheet from sticking to the polarizing plate even in the case where the prism sheet is disposed adjacently to the polarizing plate for the purposes of reducing the thickness of a liquid-crystal display device, increasing the size of the same, and improving the luminance of the same.
According to the present invention, there is provided a polarizing member which has a reflection type polarizing plate capable of separating natural incident light into reflected light and transmitted light to thereby obtain polarized transmitted light, and a fine concave-convex structure disposed on a single surface of the reflection type polarizing plate, wherein: the fine concave-convex structure has a center-line average roughness Ra of from 0.011 to 0.1 xcexcm; the fine concave-convex structure has ten or more convex portions with a height of from 0.5 to 1.0 xcexcm and two or less convex portions with a height larger than 1.0 xcexcm on any 1 mm-long line segment; and the fine concave-convex structure has a surface hardness of from H to 4H in terms of pencil hardness.
According to the present invention, on the basis of the fine concave-convex structure which is fine and has a moderate surface hardness, sticking to an adjacent optical sheet can be prevented and the adjacent optical sheet can be prevented from being injured. Moreover, the diffusing effect of the fine concave-convex structure can prevent interference fringes from occurring even in the case where the fine concave-convex structure is adjacent to the prism sheet. As a result, a large-area liquid-crystal display device which is thin, excellent in luminance and excellent in display quality, or the like, can be formed.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.